Replica molding is discussed in “Complex Optical Surfaces Formed by Replica Molding Against Elastomeric Masters”, by Younan Xia, et al, the contents of which are herein incorporated by reference. Complex, optically functional surfaces in organic polymers can be fabricated by replicating relief structures present on the surface of an elastomeric master with an ultraviolet or thermally curable organic polymer, while the master is deformed by compression, bending, or stretching. The procedure discussed was used to fabricating surfaces with complex, micrometer and submicrometer-scale patterns, including (i) diffraction gratings with periods smaller than the original grating; (ii) chirped, blazed diffraction gratings (where the period of a chirped grating changes continuously with position) on planar and curved surfaces; and (iii) patterned microfeatures on the surfaces of approximately hemispherical objects (for example, an optical surface similar to a fly's eye). These topologically complex, micropatterned surfaces are difficult to fabricate with other techniques. Xia discusses that replica molding of an organic polymer (for example, polyurethane, polymethylmethacrylate, or epoxy) against an elastomeric master [made, for example, of poly (dimethylsiloxane) (PDMS)], while that master is deformed, provides a strategy for the fabrication of complex micropatterns on surfaces. Deformation of the elastomeric master, followed by replication of the structures present on the surface of the deformed master in the rigid polymer, provides a route to structures that would be impractically difficult to generate through other procedures. Molding and embossing of organic polymers against right masters is used to manufacture optically functional microstructures such as diffraction gratings.
Replica molding to form diffractive optics is also discussed in “From Micro- to Nanofabrication with Soft Materials”, by Stephen R. Quake, et al, which is herein incorporated by reference. Quake discusses the use of soft materials such as elastomers in replica molding. According to Quake, advantages of replica molding include the fact that resolution is determined by the mold feature size, not by the optical diffraction limit. The molds are reusable, and thus their cost and fabrication difficulty do not factor substantially into the final cost of a mass-produced device. The molds can be produced with electron beam lithography, a time-consuming and expensive process that has the ability to make nanometer-scale features. Quake discusses the fabrication of diffractive optical lenses, beam splitters, and other optical elements using the replication molding step for high-fidelity pattern definition of optical nanostructures.
In “Soft Lithography”, by Younan Xia, et al., which is hereby incorporated by reference, Xia discusses the use of soft lithography as a non-photolithographic strategy based on self-assembly and replica molding for carrying out micro- and nanofabrication. In soft lithography, an elastomeric stamp with patterned relief structures on its surface is used to generate patterns and structures with feature sizes ranging from 30 nm to 100 m. Replica molding techniques are discussed, which allow duplication of three-dimensional topologies in a single step; it also enables faithful duplication of complex structures in the master in multiple copies with nanometer resolution in a simple, reliable, and inexpensive way. Replica molding against a rigid mold with an appropriate material (usually a thermoplastic polymer) has been used for the mass-production of a wide range of structured surfaces such as compact disks, diffraction gratings, and holograms. Xia discloses extending the capability of this procedure by molding against elastomeric PDMS molds rather than against rigid molds; the use of elastomers makes it easier to release small, fragile structures.
Prior art systems do not discuss the possibly of multiply patterning optical articles as taught by the invention. Thus, there has been a need for improved methods and systems for multiply patterning optical articles.